Process for the production of press-molding masses by condensation of phenols with formaldehyde or substances that yield formaldehyde



Patented Nov. 20, 1934 raocEss' r-oa 'rnn raonuo'rron. or

PRESS-MOLDING MASSES BY CONDENSA- TION OF PHENOLS WITH FORMALDE- HYDEon. SUBSTANCE-S- THAT YIELD FORMALDEHYDE many, assignor Max Koebner,Ludwigshafen-on:the-Rhine, Ger-,

of Germany to F. Rascln Ludwigshafen-on-the-Rhine, Germany, a firm G.in. b. H

No Drawing. Application February 24, 1933, 3511.1 No. 658,434. InGermany February 27,

-6Claims.

The subject matter of the invention is a process for the production ofpress-molding masses by condensation of phenols with formaldehyde orsubstances that yield formaldehyde.

Press-molding masses consisting of products of the condensation ofphenols with formalde hyde have already been abundantly prepared, but

the masses, that have mostly been employed, of

resoles and filling agents had the disadvantage.

that the properties of the pressed bodies were unfavorably afiected bythe filling agents-e. g., when using wood as filling agent, byattraction of water, and, in the caseof other filling agents, bydeterioration of the external condition. Above all, it has beenimpossible to obtain glassclear products. 4 The employment of resoleswithout filling agents is impossible on account of their easy,fusibility. i

It is true that it has already been propose to convert the resoles byhardening more or less completely into resitols and only to press thisproduct. No faultless results, however, have hitherto been obtained. Itis true that in certain circumstances glass-clearproducts could beobtained, but they had considerable defects.

A press-molding mass must fulfil the following requirements:

(1) Great velocity of hardening,

(2) Correctly proportioned fluidity which depends on the one hand on theviscosity and, on the other hand, on the velocity of hardening and isdeterminative of the ability to be pressed, especially for the correctfilling out of the molds,

(3) Suflicient stability of shape of the finished pressed piece at160-180 C.

Now it has been found that a press-molding mass, which fulfils all theserequirements, can be obtained only on observing quite definiteconditions in the manufacture, which, although they are partially knownper se, have not hitherto been employed together in the correct manner.

In the first place, the initial material must have a definite.composition. It has been recognized that only such press-molding massesare usable, in which, to each molecule of phenol, a total of more than 1preferably 2, molecules of formaldehyde or the corresponding quantity ofagents that give methylene groups and split 01! formaldehyde areemployed; It is immaterial whether,-in the production of the resins, onestarts with phenol and combines this with the necessary quantity offormaldehyde, or whether tity of formaldehyde, or whether, novolaksarecombined with hexamethylene tetramine or with the necessary quantityof formaldehyde or with both together. It is only essential that-in theinitial resin more than 1 preferably 2, molecules of methylene groupsare employed to 1 molecule of phenol. The basis of this requirement liesin the knowledge that only in this way can pressed bodies be obtainedwhich when hot possess the stability of shape that is necessary for thepress technician, because press-molding= massesv which are made offormaldehyde and phenols in the proportion of less than about 1%.molecules of formaldehyde to 1 molecule of phenol and which are freefrom filling agents, give pressed bodies which are too soft.

Even on observing the proportions stated, a v usable press-molding masscould not be obtained.

For this purpose, the resin must be hardened to such a degree that, inthe finely powdered condition, it does not sinter even at a tempera-,ture of about '70 to 100 C., but it must not become too firm because itwould then not possess the necessary fluidity.

' The hardening methods hitherto proposed are, especially in connectionwith a phenoplastthat hardens 'as rapidly as the present one such as itis essential for it to be for fulfilling'the require-' ment 3, quiteinapplicable, because the hardening cannot be retained at the suitablecondition.

To obtain the correct hardening, the fusible resin that is obtained bycondensation of the initial substances in such a proportion that morethan 1 molecules of methylene groups are employed to 1 molecule ofphenol, must be hardened at a moderate temperature, with supervision ofthe progress of the hardening or of the diminution of the fluidity,until the solidified resin gives a powder that does not sinter at aboutto 100 C. The observation of the correct temperature during thehardening is advantageously effected by filling flat molds, whosethickness should not exceed about 10 cms., with the resin and warmingthem in a liquid bath, preferably in a water bath, at about 50-70? C. Inthe case of thickermolds, the

heat of reaction produced on hardening would not be capable of beingcarried away sufllciently rapidly and the resin would, at least in'themiddle of the mold, very rapidly become quite hard and unusable. Thesame disadvantage would occur it higher temperatures than about 70 werechosen for the heat of the water bath. The employment of a water bath isto be preferred, because, in an air bath for example, which,

although it can act in a heating manner, cannot also act in a coolingmanner, an undesirably rapid and uncontrollable hardening of the resincould easily occur.

With these precautionary measures, there is obtained a gradual hardeningof the resin which extends over some days. In order that the limit ofhardening that is favorable for the object in view shall not beexceeded,-the progress of the hardening must be constantly supervised.As a means for this purpose, a steel needle maybe used which, loaded bya weight, penetrates more slowly into the resin as it becomes harder.The

' hardening of the resin is stopped as soon as the 15 velocity of thepenetration of the steel needle has fallen to a certain degree that isdetermined by experience.

Instead of the hardening, the decrease of the fluidity can besupervised, the determination of which is advantageously effected byKrahls method (Elektrotechnische Zeitschfift, 1931,

page 439).

By means of continuous supervision of the resin, one is in a position todetermine exactly the point of time at which the resin has reached thehigh melting point that is necessary for the further treatment, whilemaintaining a fluidity that is sufiicient for the pressing. If hardeningis carried on for a longer time, one would be in a position to ascertainwith the same method the gradually occurring deterioration of thefluidity. In this manner one has an infallible means at hand ofcontrolling the progress of the hardening process and of protectingoneself from defective results.

However, even such a resin would still be unusable for the object aimedat. The resin may, in accordance. with its method of manufacture,contain water, ammonia or both, and these would detrimentally affect itscompressi bility as well as the appearance of the pressed bodies andtheir usefulness. The hardened resin is consequently pulverized and thepowder is then freed from water, ammonia and other volatile substances,preferably by heating at temperatures between about 80 and 100 C. and invacuo.

Example 1 A resole is prepared in a known manner from 940 parts of purephenol, 1000 parts of 30% formaldehyde and 14 parts of hexamethylenetetramine, and a filtered solution of 230 parts of hexamethylenetetramine in 230 parts of water is then absorbed. This mixture is freedfrom water by vacuum distillation, the temperature gradually rising toC. The mass is kept in vacuo for three more hours at this tempera- Iture.

The yellow resin of the consistency of honey that is obtained in thismanner is now poured into metallic molds which are 60-100 cms. deep,15-20 cms. wide and 6 up to a maximumof 10 cms. thick. -The molds aresuspended in a water bath at 60 C. It can be observed, on a thermometerwhose mercury bulb is placed in the centre of the resin, that thetemperature gradually rises to 70 C. on account of the reaction whichoccurs. The constantly progressing hardening is followed with aninstrument which is constructed similarly to the known Vikat needle. Itconsists of a steel needle with a cross-sectional area of about 2 squaremillients and then examined as to its fluidity by the aforesaid Krahlsmethod. Experiments have shown that a fluidity of 100 to 200 mms. at apressure of 300 kgs. per sq. cm. corresponds, with an accuracy that issufficient for'practical purposes, to the degree of hardness determinedin the manner stated with the Vikat needle.

As soon as the resin shows the correct nature as determined in oneof themanners stated, the molds with the resin are transferred from the warmwater baths into cold water baths. The cooled resin is converted into afine powder and is kept for from 1 to 2 hours at a temperature of 70 to100 C. in vacuo in a vacuum drier, so that the water and ammoniacontained in the resin are evaporated. A powder prepared in this mannergives, on pressing at 160 to 180 C. pressed articles which can be pushedout of the mold without becoming deformed andare'yellow without furthercoloration and clearly transparent.

Example 2 Example 3 1000 parts of phenol, 1000 parts of formaldehyde and230 parts of hexamethylene tetramine are heated for 2 hours at 60 C. Itis also possible to use more formaldehyde and correspondingly lesshexamethylene tetramine or vice versa. The water is then distilled offwith a good vacuum and the resin is heated until it reaches atemperature of 60 C. Thereupon, the resin is kept for a further 2 to 3hours at 60 C. and is then. worked up further as in Example 1.

Larger quantities of formaldehydeand agents which split off formaldehydemay be employed in the examples. Instead of phenol, suitable cresols orother phenols may be employed. If desired, the temperature in thehardening may be kept somewhat lower than 50 C. or somewhat higher than70 C., the former giving a retardation and the latter an acceleration ofthe hardening process. Instead of the water bath there may be employedanother liquid bath or, with careful working, an air bath. Instead ofthe Vikat needle and Krahls method, other supervising methods for theprogressing hardening may be employed. The .freeing of the powderedresin from volatile substances may also be effected at a lowertemperature and without vacuum.

There can be added to the resin, at any desired stage during themanufacture, l to. 5% of stearic acid and other flowing agents for thepurpose of increasing the fluidity. There can also be added to theresins small quantities of salicylic acid or other carboxylic acids ofthe aromatic series which, in a quantity of up to 10%, have the propertyof rendering any too large a quantity of water, which may be present inthe finished products and which, in certain circumstances, would producea turbidity, harmless in this direction. Any desired quantities andkinds of organic and inorganic dyestuffs may also be added to theresins.

Without admixture of any kind, the pressmolding masses produced in theabove manner, give, on being worked up under pressure and heat, pressedbodies which are clearly transparent and colorless or of a yellow color.

The above press-molding masses may be employed for the production of allkinds of pressed articles for electrotechnical, household, orna-'-mental and fancy purposes. Pressed bodies from masses according to theabove process possess an excellent power of resistance to water.

I claim:--

1. A process for the production of press-moldingmasses by condensationof phenols with formaldehyde, comprising condensing the initialsubstances, in such proportions that more than 1 molecules of methylenegroups are employed to 1 molecule of phenol, into a fusible resin,hardening said fusible resin in layers which do not exceed 10centimeters in thickness at a temperature ranging from'about 50 to about0., with supervision of the progress of the hardening until thesolidified resin gives a powder that does not sinter at about '70 to 1000., pulverizing the hardened resin, and freeing the powder from volatilesubstances.

2. A process for the production of press-mold-' ing masses bycondensation of phenols with formaldehyde, comprising condensing theinitial substances in such proportions that more than 1 molecules ofmethylene groups are employed to 1 molecule of phenol, into a fusibleresin, hardening said fusible resin in layers which do not exceed 10centimeters in thickness at a temperature ranging from about 50 to about70 0., with supervision of the diminution of its fluidity, until thesolidified resin gives a powder that does not sinter at about 70 to 100C. pulverizing the hardened resin and freeing the powder from volatilesubstances. 3. A process for the production of press-mold ing masses bycondensation of phenols with formaldehyde, comprising condensing theinitial substances, in such proportions that more than 1 /2 molecules ofmethylene groups are employed to 1 molecule of phenol, into a fusibleresin, hardening said fusible resin in layers which do not exceed 10centimeters in thickness at a temperature ranging from about 50 to about70 0., with supervision of the progress of the-hardening, until thesolidified resin gives a powder that does not sinter at about 70 to 1000., pulverizing the hardened resin, and freeing thepowder from volatilesubstances by heating at between about 80 and 100 C. and in vacuo.

4. A process for the production of press-molding masses by condensationof phenols with formaldehyde, comprising condensing the initialsubstances, in such proportions that more than 1 molecules of methylenegroups are employed to 1 molecule of phenol, into a fusible resin,hardening said fusible resin in layers which do not exceed 10centimeters in thickness by heating it at about .60 to 70 C. withsupervision of the progress of the hardening, until the solidified resingives a powder that does not sinter at about'70 to 100 0., pulverizingthe hardened resin, and freeing the powder from volatile substances.

5. A process for the production of pressmolding masses by condensationof phenols with formaldehyde, comprising condensing the initialsubstances, in such proportions that more than 1 molecules of methylenegroups are employed to 1 molecule of phenol, into a fusible resin,hardening said fusibleresinin layers which do not exceed 10 centimetersin thickness by heating it at about 60 to 70 0. in said form. of layersnot exceeding 10 cm. in thickness, in a liquid bath, with supervision ofthe progress of the hardening, until the solidified. resin gives apowder that does not sinterfat about 70 'to 0., pulverizing the hardenedresin and freeing the powder from volatile substances.

6. A process for the production of pressmolding masses by condensationof phenols with formaldehyde, comprising condensing the initialsubstances, in such proportionsthat more than 1 /2 molecules ofmethylenegroups are employed to 1 molecule of phenol, into a fusible resin,hardening said fusible resin in layers which do not exceed 10centimeters in thickness by heating it at about 60 to 70 0., withsupervision of the diminution. of its fluidity, until the solidifiedresin gives a powder that does not sinter at about '70 to 100 0.,pulverizing the hardened resin and freeing the, powder from volatilesubstances.

. MAX KOEBNER,

